Serotonin 5-HT2 receptor imaging in major depression: focal changes in orbito-insular cortex

BACKGROUND

Serotonin receptors may play an important role in the pathophysiology of affective disorders. We studied type-2 serotonin (5-HT2) receptors in the brain of patients with major depression.

METHOD

Using positron emission tomography (PET) and the selective radioligand [18F]altanserin, we investigated 5-HT2 receptor distribution in eight drug-free unipolar depressed patients and 22 healthy subjects. Data were analysed using Statistical Parametric Mapping 95.

RESULTS

In depressed patients, [18F]altanserin uptake was significantly reduced in a region of the right hemisphere including the posterolateral orbitofrontal cortex and the anterior insular cortex. A trend to similar changes was found in the left hemisphere. No correlation was found between the uptake and the Hamilton rating scale score.

CONCLUSIONS

Pathophysiology of depression may involve changes in 5-HT2 receptor in brain regions selectively implicated in mood regulation.

[Analysis of intensity of post-stroke depression and its relationship with the cerebral lesion location]

BACKGROUND

Several studies have suggested a close relationship between intensity of poststroke depression and lesion location, but the relationships are not clear for some authors. In this study we try to test the hypothesis that the intensity of depression in an early stage (4th week) of cerebral vascular accidents (CVA) in related to lesion location and type of lesion.

PATIENTS AND METHODS

In a sample of one hundred and thirty patients in the fourth week of the evolution of an unilateral CVA, 48 patients fulfilled research diagnostic criteria (RDC) of post-stroke depression (34 major depression; 14 minor depression). Schedule for Affective Disorders and Schizophrenia (SADS) and standard measures of intensity of depression (Hamilton's HRDS, Montgomery-Asberg's MADRS and Beck's BDI) were used.

RESULTS

In the fourth week of the evolution of CVA's, depression intensity measures (HRDS and BDI) were significantly higher in anterior lesion when compared to posterior lesions. No significant differences were found between right and left lesions, but both were higher than in non-hemispheric lesions. No significant differences of prevalence or intensity of depression were found in relation to lesion type (hemorrhagic/ischaemic).

CONCLUSION

The results confirm a relationship between intensity mood disorders after a cerebral vascular accident and the topography of the lesion.

Brain glucose metabolism in borderline personality disorder

We searched for regional cerebral metabolic disturbances in patients with borderline personality disorder (BPD). Ten inpatients with BPD, no current DSM-IIIR Axis I diagnosis and free of any psychotropic substances, were compared with 15 age-matched control subjects using positron emission tomography with 2-deoxy-2-[18F]fluoro-D-glucose and semiquantitative analysis of regional glucose metabolic activity. We found relative hypometabolism in patients with borderline personality disorder at the level of the premotor and prefrontal cortical areas, the anterior part of the cingulate cortex and the thalamic, caudate and lenticular nuclei. This study shows significant cerebral metabolic disturbances in patients with borderline personality disorder. These metabolic disturbances, which are similar to some of those described in other psychiatric entities, may help to understand the characteristic clinical aspects of this disorder.

No association between bipolar affective disorder and a serotonin receptor (5-HT2A) polymorphism

The serotonergic system is implicated in the pathogenesis of affective disorders. In particular, the role of the postsynaptic 5-hydroxytryptamine (serotonin) type 2 receptor (5-HT2) has been documented by several studies. The 5-HT2A receptor gene located on chromosome 13 (13q14-21) can be considered a candidate gene for bipolar affective disorder (BPAD). We tested association between a 5-HT2A receptor DNA variant and BPAD using a case-control design. Eighty-three BPAD patients and 129 unrelated normal controls, carefully matched for sex and geographical origin, were studied. Allele and genotype frequencies as well as homo-heterozygote distribution at the 5-HT2A receptor polymorphism were compared between the two groups. No significant allelic or genotypic associations were observed. There was no significant difference for homo-heterozygote distribution between the two groups. These preliminary results may indicate that in our sample the 5-HT2 receptor polymorphism studied is unlikely to play a role in the genetic susceptibility to BPAD.

Distribution of delta activity across nonrapid eye movement sleep episodes in healthy young men

The distribution of delta activity across successive nonrapid eye movement (NREM) sleep episodes and its night-to-night stability across three consecutive nights were investigated by studying delta power with spectral analysis in 31 healthy young men. Repeated-measures analysis of variance (ANOVA) with polynomial contrast was applied to grouped data of absolute delta power and three indexes: (1) the rate of delta power per NREM episode to its duration, 2) the standardized rate for the last NREM episode, and 3) the logarithm of the standardized rate. A significant linear decrease across NREM episodes was observed for each variable in each successive night. In addition, using night as a second within-subjects factor, no night effect was observed. Yet, the subsequent analysis of the logarithmic data yielded greater F values in all three nights' data as well as a linear function that accounted for a greater proportion of total variance than the analysis of the nonlogarithmic data. Since a linear decline for the logarithm of a variable implies an exponential distribution for that variable, we conclude that delta activity is distributed exponentially across NREM episodes, and this finding shows a remarkable night-to-night stability.

Clinical and psychosocial predictors of recurrence in recovered bipolar and unipolar depressives: a one-year controlled prospective study

Unipolar and bipolar patients with a chronic illness pattern were investigated to evaluate the relevance of clinical and psychosocial risk factors to predict subsequent recurrence. Self-esteem, social adjustment, social support and attributional style were assessed in 27 recovered bipolar patients, 24 recovered unipolar patients maintained on lithium or antidepressant prophylaxis and 26 healthy controls. They were further interviewed every 2 months in a 1-year period in order to diagnose affective episodes according to Research Diagnostic Criteria. Survival analyses and Cox's regressions demonstrated that being a unipolar patient and showing poor social adjustment were the strongest predictors of the occurrence of affective episodes. Self-esteem, social support, attributional style and clinical characteristics, such as age at illness onset, number of previous episodes or of previous hospitalizations and presence of affective disorder in first-degree relatives, were not found to be risk factors for further recurrence. This study stresses the importance of social adjustment in evaluating the outcome of affectively ill patients maintained on medication prophylaxis.

Association study of bipolar disorder with candidate genes involved in catecholamine neurotransmission: DRD2, DRD3, DAT1, and TH genes

Despite strong evidence for genetic involvement in the etiology of affective disorders (from twin adoption and family studies), linkage and association methodologies are still exploring the nature of genetic factors in these diseases. Interesting testable hypotheses have been described, including candidate genes involved in catecholamine neurotransmission. We studied 69 bipolar patients and 69 matched controls (for age, sex, and geographical origin) for association and linkage disequilibrium with DNA markers at the following genes: the tyrosine hydroxylase gene, dopamine transporter gene, and dopamine D2 and D3 receptor genes. Association and linkage disequilibrium were excluded between bipolar affective disorder and these four candidate genes in our sample.

TRH stimulation and dexamethasone suppression in borderline personality disorder

The link between borderline personality disorder (BPD) and affective disorders is controversial. The dexamethasone suppression test (DST) and the thyrotropin-releasing hormone (TRH) stimulation test, which are useful in the study of affective illness, might help to elucidate this possible link. This report assessed these endocrine tests in a sample of 20 borderline patients without a concomitant diagnosis of major depression (but showing depressive symptoms) in comparison to a group of sex- and age-matched patients with major depressive disorder (MDD) without BPD. Only 5 of our BPD patients were DST nonsuppressors compared to 13 MDD patients at a threshold of 50 micrograms/L. With a threshold of delta max TSH < 5 microU/mL following TRH, 1 BPD patient showed a blunted TSH response compared to 9 MDD patients. BPD patients displayed significantly less perturbed tests. These results show no evidence of an endocrine biological link between BPD and the MDD. The depressive symptoms observed in BPD patients might not have the same biological substrates as those found in patients with MDD.

Life events and primary affective disorders. A one year prospective study

BACKGROUND

Unipolar and bipolar patients with a chronic illness pattern were investigated to determine whether they experienced a higher number of life events prior to the onset of recurrent affective episodes.

METHOD

The study participants consisted of 27 recovered bipolar patients, 24 recovered unipolar patients and 26 healthy control subjects. Life events and psychiatric status were assessed by bimonthly interviews over the period of one year using the Inventory for Recent Life Events and the Research Diagnostic Criteria.

RESULTS

In both unipolar and bipolar patients, analyses revealed no significant differences in the number of life events experienced, irrespective of whether the patients had presented with a depressive episode of at least minor intensity during the study (all P > 0.1). Specifically, an increase in marital problems was observed in bipolar patients prior to the onset of recurrent hypomanic and manic episodes (P = 0.06).

CONCLUSION

The causal association between life events and the onset of depression, shown to be relevant in non-chronically depressed subjects, does not apply in chronic affective disorders. In addition, our results suggest that marital events have an impact on the onset of recurrent hypomanic and manic episodes.

Neuroendocrine and sleep variables in major depressed inpatients: role of severity

To evaluate the reliability of the endogenous concept of depressive illness according to the Newcastle Endogenous Depression Diagnostic Index (NEDDI), 155 major depressive inpatients with NEDDI scores > or = 6 (endogenous) were matched for gender and age (+/- 5 years) to 155 major depressive inpatients with NEDDI scores < 6 (nonendogenous). When sleep polygraphic variables, neuroendocrine parameters (dexamethasone suppression and thyrotropin-releasing hormone tests), and various clinical variables (unipolar/bipolar status, psychotic/nonpsychotic subtype, and severity of the depressive episode) were examined, statistically significant differences between endogenous and nonendogenous patients emerged for three variables: the thyroid-stimulating hormone response to the thyrotropin-releasing hormone test, the dexamethasone suppression test response at 16:00 h, and the percentage of time awake during the night. However, when the effects of age and severity of depression were controlled, those differences disappeared.

Psychosocial predictors of major affective recurrences in bipolar disorder: a 4-year longitudinal study of patients on prophylactic treatment

A total of 21 recovered bipolar patients on prophylactic treatment were prospectively followed up for a period of 1 year. Data for major recurrences were retrospectively collected for an additional 3-year period. During the entire 4-year period, over half of the patients (52%) had no major affective recurrences. Eight patients experienced a major depressive episode, while only two experienced a manic one. Psychosocial and clinical variables were assessed at entry to the study. The effect of these variables on the subsequent 4-year illness course was analysed using survivorship curves. The results show that the following psychosocial variables significantly predicted the occurrence of a major affective episode: low level of social support, maladjustment in social and leisure activities, and poor quality of relationships with extended family. In contrast, clinical variables which characterize illness history were not significantly associated with major recurrences.

Interregional correlation of cerebral glucose metabolism in unmedicated schizophrenia

To investigate metabolic relationships between different brain regions in schizophrenia, we measured regional brain metabolism using positron emission tomography (PET) and [18F]fluorodeoxyglucose (FDG) in 15 unmedicated schizophrenic patients and 15 healthy subjects. We analyzed correlations between glucose metabolism data of multiple brain regions using factorial analysis and correlation coefficient comparisons. Absolute regional intercorrelations in schizophrenic brains were found to be significantly stronger than in controls, in relationship to the greater variability of metabolic rates in schizophrenic patients. Variability of normalized metabolic rates and regional intercorrelations were not significantly different between schizophrenic patients and control subjects. We conclude that a global metabolic factor accounts for the variability of metabolic data in untreated schizophrenia.

Linkage analysis of families with bipolar illness and chromosome 18 markers

Linkage of bipolar (BP) illness with chromosome 18 markers located at 18p11 was recently reported. A possible role for chromosome 18 in the etiology of BP illness was implicated previously by the finding in three unrelated patients of a ring chromosome with breakpoints and deleted segments at 18pter-p11 and 18q23-qter. To test the potential importance of a gene defect on chromosome 18 in our material, we examined linkage with chromosome 18 markers in two families with multiple patients with BP illness or BP spectrum disorders. fourteen simple tandem repeat polymorphisms were used located in the chromosomal region 18p11 to 18q23 and separated by distances of approximately 10 cM on the genetic map. In one family linkage to chromosome 18 could not be excluded. Linkage and segregation analysis in the family suggests that the 12-cM region between D18S51 and D18S61 located at 18q21.33-q23 may contain a candidate gene for BP illness.

Sex difference in 5HT2 receptor in the living human brain

Serotonergic mechanisms are involved in gender-related behaviors and psychiatric conditions like aggression, eating disorders, depression, impulsivity or suicide. We studied gender differences in the living human brain type-2 serotonin receptor (5HT2r). Twenty-two healthy age-matched men and women were investigated using positron emission tomography and the selective radiotracer, 18F-labeled altanserin. Binding was quantified using a non-linear least-squares minimization procedure. We found significantly higher 5HT2r binding capacity in men than in women, especially in the frontal and cingulate cortices. Distinct liability for men and women to suffer from some psychiatric disorders responding to serotonergic agents may be related to differences in brain serotonin receptors.

A linkage study between bipolar disorder and genes involved in dopaminergic and GABAergic neurotransmission

Neurobiological studies indicate a dysregulation of the dopaminergic and GABAergic neurotransmission in bipolar disorder. We examined two large families segregating bipolar disorder, for linkage with the genes encoding dopamine beta-hydroxylase, the dopamine transporter DAT1, the dopamine D2, D3 and D5 receptors, and the alpha-1, alpha-5 and beta-1 subunits of the GABAA receptor. Under at least one diagnostic model one of the two families provided evidence to exclude linkage for the DAT1, DRD2, DRD3, DRD5, DBH, GABRA1 and GABARB1 genes but could not exclude the GABRA5 locus. A second family excluded only the GABRA1 and GABRA5 loci at zero recombination and could not formally reject linkage at the DBH, DRD2, DRD3, DRD5, DAT1 and GABARB1 loci. Further analyses at these loci are warranted.

Sleep EEG analysis by linear prediction: frequency changes of slow-wave activity within NREM and REM sleep episodes in healthy men

The linear prediction method was applied to obtain a power spectra estimate of sleep EEG in 10 healthy young men. In order to analyze frequency changes of the slow-wave activity (EEG power in the delta band, 0.05-2.88 Hz), the delta mean frequency was computed for each 20-second sleep epoch. A mean delta mean frequency was calculated for each sleep stage in each individual. Our observations indicate that the delta mean frequency decreases during NREM periods and increases mainly at the onset of the REM episodes. This finding, in parallel with the detailed analysis of slow-wave power variations, leads to an additional description of sleep characteristics during transitions between the NREM-REM sleep episodes.

Basal ganglia and frontal lobe glucose metabolism. A reproducibility positron emission tomography study

Positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG) is frequently used to study the metabolic correlates of movement and mental disorders. These studies generally focus on changes in the frontal cortex and the basal ganglia. The reproducibility of glucose metabolism estimates in these structures was tested in 13 normal subjects studied at rest using a standard and simple protocol. A reproducible dorsoventral metabolic gradient was demonstrated in the frontal cortex. Such a gradient was not present in the basal ganglia when the upper region of interest in the caudate nucleus, where the lower metabolic rate of glucose was probably attributable to partial volume effects, was not considered. Absolute values of glucose metabolic rates varied by 6.4 to 12.5% in the frontal cortex and by 6.8 to 14.7% in the basal ganglia. Variations in normalized values in the basal ganglia ranged from 4.0 to 8.6%. The number of subjects required to detect statistical differences in group comparison or in test-retest studies was calculated for different anticipated levels of change. With the variability detected in this experiment, less than 10 subjects were expected to be sufficient to detect a 15% change in most regions and in both types of studies.

Altered frontostriatal relationship in unmedicated schizophrenic patients

Positron emission tomography with [18F]-fluoro-2-deoxy-D-glucose as tracer was used to investigate frontal glucose metabolism in 15 unmedicated schizophrenic patients and 15 healthy subjects under resting conditions. Although no difference in absolute frontal cerebral metabolic rates of glucose (CMRglu) were found between schizophrenic patients and control subjects, relative measures significantly differentiated the two groups. Whole frontal metabolism and frontocaudate ratio were significantly decreased in both hemispheres in the patients. The results confirm the existence of hypofrontality in unmedicated schizophrenia and indicate disturbances in metabolic relationships between the frontal cortex and the striatum in this disorder.

[Decrease in the frontal-superobasal metabolic ratio in unipolar depression]

Cerebral frontal glucose metabolism was investigated in 12 unipolar depressed patients and compared to these of 12 healthy volunteers using Positron Emission Tomography (PET) and (F18) fluorodeoxyglucose. The PET investigation was made in a quiet room with a dimly light and each subject remained in a resting state with closed eyes. Results show a decreased in a frontal superobasal calculated ratio in depressed patients compared to control subjects for left and for right values. This reduction indicates an imbalance between the frontal and the superobasal region. This imbalance could relate to some particular depressive symptom profile.

Acute, subchronic and withdrawal sleep EEG changes during treatment with paroxetine and amitriptyline: a double-blind randomized trial in major depression

Paroxetine (30 mg), a selective serotonin (5-HT) reuptake inhibitor, was compared in a double-blind trial to amitriptyline (150 mg) in a sample of 40 inpatients aged 18-65 years who fulfilled Research Diagnostic Criteria for major depression. Patients were studied after a placebo drug washout period of 10 days and after an active 4-week treatment period. Sleep EEG recordings were performed before and at the end of the study as well as during acute treatment (first 2 days) and following withdrawal of active medication. Paroxetine shows an antidepressant effect similar to amitriptyline with a different side-effect profile typical of 5-HT reuptake inhibition. Paroxetine and amitriptyline decreased the amount of REM sleep, a well-known effect of classical antidepressants. Paroxetine also shared with other 5-HT reuptake inhibitors an alerting effect on sleep that was not shown to be detrimental on subjective sleep quality.

Relationship between the Newcastle scale and sleep polysomnographic variables in major depression: a controlled study

In order to investigate the reliability of the endogenous concept of depressive illness with some sleep EEG parameters, we studied 39 male inpatients suffering from a nonbipolar major depressive episode (15 endogenous (MDDE) and 24 nonendogenous (MDDNE)) and 20 age and sex matched normal controls (C). All patients were diagnosed according to the Research Diagnostic Criteria (RDC) and the endogenous character of the episode was assessed with the Newcastle Endogenous Depression Diagnostic Index. We found significant differences for the following variables between the three groups (MDDE, MDDNE and C): sleep period time (SPT), REM latency, stage II, slow wave sleep (SWS), REM latency expressed as a continuous variable and REM latency expressed as a dichotomizing variable with a threshold of 50 min. These variables were used to compare the endogenous and the nonendogenous depressed patients and also the major depressed patients and the normal controls. Significant differences were observed between all depressed patients and control subjects for amount of SWS and REM latency which were both reduced in endogenous and nonendogenous depressed patients. No significant difference was observed between endogenous and nonendogenous depressed patients, except for the REM latency expressed with a threshold of 50 min (more frequently observed in endogenous depressed patients). Our data support the observation that SWS and REM latency are decreased in major depressive patients. However, in this age and sex controlled study, subtyping nonbipolar major depressive disorder for an endogenous character by the Newcastle Endogenous Depression Diagnostic Index (NEDDI) did not reveal further significant differences for sleep EEG variables, except for the shortening of the REM latency expressed as a dichotomizing variable.

[Heredity and manic-depressive psychosis]

The present article reviews the basic and recent findings of the genetics in manic-depressive illness. The different molecular genetic techniques that have been applied to this research field are presented. Results of linkage and association studies are discussed in regard to the main limitations of these approaches in psychiatric disorders. On the whole, linkage and association studies contributed to the localisation of some potentials vulnerability genes for manic-depression on chromosomes X and 11 and more recently 18.

Efficacy of the 'clonidine REM suppression test (CREST)' to separate patients with major depression from controls; a comparison with three currently proposed biological markers of depression

We have shown that clonidine, infused i.v. during the second non-REM period, was significantly less REM sleep suppressant in depressed patients than in control subjects. We have named this procedure the 'clonidine REM suppression test (CREST)'. In this report, we compare in the same sample (15 patients with primary major affective illness, 10 normal controls, 15 patients with minor depression and 15 patients with generalized anxiety) the efficacy of the CREST to separate the major depressed patients from the control subjects with the efficacy of three currently proposed biological markers of depression, i.e., the latency of REM sleep, the dexamethasone suppression test and the clonidine growth hormone stimulation test. We found that the CREST had the highest efficacy and suggest that further studies with independent and larger samples of patients and controls are needed to confirm those preliminary results and establish if the CREST could provide a new biological marker of major affective disorders.